﻿PYCNOBONTID^;. 
  

  

  203 
  

  

  P. 
  1336. 
  Smaller 
  imperfect 
  head 
  and 
  trunk, 
  wanting 
  the 
  greater 
  

   part 
  of 
  the 
  fins 
  ; 
  Tarnhill, 
  Tewkesbury, 
  Gloucestershire. 
  

  

  Egerton 
  Coll. 
  

  

  P. 
  5127. 
  Very 
  small 
  imperfect 
  trunk, 
  with 
  abraded 
  scales 
  showing 
  

   the 
  tubercular 
  ornament 
  in 
  part; 
  Langport, 
  Somerset- 
  

   shire. 
  Purchased, 
  1886. 
  

  

  Mesodon 
  rugulosus 
  (Agassiz). 
  

  

  1825. 
  Figure 
  by 
  C. 
  Prevost, 
  Ann. 
  Sci. 
  Nat. 
  vol. 
  iv. 
  pi. 
  xviii. 
  fig. 
  18. 
  

   1837. 
  Pycnodus 
  trigonus, 
  W. 
  Buckland, 
  Geol. 
  & 
  Mineral., 
  ed. 
  2, 
  vol. 
  ii. 
  

  

  p. 
  45, 
  pi. 
  xxvii. 
  c. 
  fig. 
  3. 
  

   1839-44. 
  Pycnodus 
  rugulosus, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  ii. 
  

  

  p. 
  194, 
  pi. 
  lxxii. 
  a. 
  fig. 
  23. 
  

   1839-44. 
  Gyrodus 
  trigonus, 
  L. 
  Agassiz, 
  ibid. 
  p. 
  232, 
  pi. 
  lxix. 
  a. 
  fig. 
  15. 
  

  

  [Vomer; 
  British 
  Museum] 
  1 
  . 
  

   1840. 
  Pycnodus 
  rugulosus, 
  R. 
  Owen, 
  Odontography, 
  pi. 
  xxxiv. 
  fig. 
  1. 
  

   1844. 
  Microdon 
  trigonus, 
  L. 
  Agassiz, 
  Tableau 
  Gen. 
  Poiss. 
  Foss. 
  p. 
  xlii. 
  

  

  (name 
  only). 
  

   1844. 
  Pycnodus 
  parvus, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  ii. 
  p. 
  199 
  

  

  (name 
  only). 
  [Mandibular 
  dentition; 
  British 
  Museum.] 
  

   1844. 
  Pycnodus 
  trigonus, 
  L. 
  Agassiz, 
  ibid. 
  p. 
  199 
  (name 
  only). 
  

   1844. 
  Pycnodus 
  latirostris, 
  L. 
  Agassiz, 
  ibid. 
  p. 
  199. 
  [Mandibular 
  

  

  dentition 
  ; 
  British 
  Museum.] 
  

   (?) 
  1871. 
  Pycnodus 
  rugulosus, 
  J. 
  Phillips, 
  Geol. 
  Oxford, 
  p. 
  179, 
  woodc. 
  

  

  xxxix. 
  fig. 
  1. 
  

   1871. 
  Gyrodus 
  trigonus, 
  J. 
  Phillips, 
  ibid. 
  p. 
  179, 
  woodc. 
  xxxix. 
  fig. 
  7. 
  

   1889. 
  Mesodon 
  rugulosus, 
  A. 
  S. 
  Woodward, 
  Geol. 
  Mag. 
  [3] 
  vol. 
  vi. 
  

  

  p. 
  454. 
  

   1889. 
  Mesodon 
  trigonus, 
  A. 
  S. 
  Woodward, 
  ibid. 
  p. 
  454. 
  

   1890-92. 
  Mesodon 
  rugulosus, 
  A. 
  S. 
  Woodward, 
  Proc. 
  Geol. 
  Assoc. 
  

  

  vol. 
  xi. 
  p. 
  298, 
  pi. 
  iii. 
  figs. 
  23-27, 
  and 
  ibid, 
  vol. 
  xii. 
  p. 
  239, 
  pi. 
  iv. 
  

  

  figs. 
  2-4. 
  

  

  Type. 
  Vomerine 
  dentition 
  ; 
  Oxford 
  Museum. 
  

  

  A 
  species 
  of 
  large 
  size, 
  known 
  only 
  by 
  the 
  head. 
  External 
  bones 
  

   ornamented 
  with 
  coarse 
  granulations, 
  closely 
  arranged 
  ; 
  maximum 
  

   width 
  of 
  preoperculum 
  exceeding 
  half 
  its 
  depth. 
  Teeth 
  ornamented 
  

   with 
  a 
  feeble 
  rugosity 
  radiating 
  from 
  an 
  annular 
  apical 
  indentation, 
  

   soon 
  removed 
  by 
  abrasion 
  ; 
  outline 
  of 
  teeth 
  usually 
  regularly 
  

   rounded. 
  Vomerine 
  teeth 
  closely 
  arranged, 
  those 
  of 
  the 
  median 
  

   series 
  considerably 
  broader 
  than 
  long 
  and 
  their 
  breadth 
  about 
  equal 
  

   to 
  that 
  of 
  the 
  two 
  lateral 
  series; 
  an 
  incomplete 
  supplementary 
  

  

  1 
  A 
  vomer 
  from 
  the 
  Bathonian 
  of 
  Pernigotti, 
  Verona 
  (de 
  Zigno 
  Collection, 
  

   University 
  of 
  Padua), 
  is 
  also 
  recorded 
  under 
  this 
  name 
  by 
  F. 
  Bassani, 
  Atti 
  Soc. 
  

   Ital. 
  Sci. 
  Nat. 
  vol. 
  xxviii. 
  (1885), 
  p. 
  161. 
  

  

  